import java.util.Scanner;


public class test {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int[] a= new int[10];
        double average = 0;
        for (int i=0;i<10;i++){
            a[i]=in.nextInt();
            average=average+a[i];
        }
        System.out.printf("%.2f",average/10);

    }
}
